Technical Field
The present disclosure relates to a control apparatus that is applicable to a motor control system. The motor control system includes a converter, an inverter, and a motor. The converter is capable of stepping up an output voltage of a direct-current power supply and outputting the stepped-up output voltage. The inverter is capable of converting the output voltage from the converter to an alternating-current voltage and outputting the alternating-current voltage. The motor is capable of being driven by the alternating-current voltage outputted from the inverter.
Related Art
As can be seen in Japanese Patent Publication No. 4635703, as this type of control apparatus, a control apparatus that sets an output voltage command value of a converter so as to reduce the total power loss of a motor control system is known. Specifically, the control apparatus holds a target value of a modulation factor as map data, in advance. The modulation factor is that at which the total power loss of the motor control system becomes minimum. The modulation factor is associated with an inter-wire voltage magnitude and a torque command value of the motor. The control apparatus sets the output voltage command value of the converter to control the actual modulation factor to the target value of the modulation factor calculated from the map data. As a result, the total power loss of the motor control system is reduced.
Here, the inventors of the invention in the present application have found that the minimum value of total power loss of the motor control system is not determined only by the modulation factor. Therefore, a plurality of parameters related to the operating state of the motor control system are required to ascertain an operation point of the motor control system at which the total power loss becomes minimum. Thus, for example, a method using map data that associates the plurality of parameters with the output voltage command value of the converter may be used as the method for setting the output voltage command value. However, in this case, there is concern that the number of steps involved in map data generation will increase, and the number of steps involved in designing of the control apparatus will increase.
Furthermore, the operation point of the motor control system at which the total power loss becomes minimum may change depending on individual differences among mass-produced motor control systems and the temperature of the usage environment of the motor control system. Therefore, the map data may be generated such as to take into consideration the effects of individual differences and usage environment temperature, to improve ascertainment accuracy regarding the operation point at which the total power loss becomes minimum. However, in this case, there is concern that the number of steps involved in designing of the control apparatus will increase.
In this way, there is still room for improvement in the techniques for setting the output voltage command value of the converter to reduce the total power loss of the motor control system.